Underwater High‐Voltage Electric Pulse‐Assisted Hydraulic Fracturing: Multiphysics Modeling Framework and 3D Dynamic Crack Propagation Analysis

This study investigates rock fracturing mechanisms and 3D crack propagation dynamics in underwater high‐voltage electric pulse‐assisted hydraulic fracturing. The study develops a multiphysics model by integrating circuit theory, plasma dynamics, and fluid–solid coupling principles. This model quantifies the interplay between plasma channel evolution, electrohydraulic shock wave (EHS) generation, and mechanical responses of rock. The model combines Kirchhoff's circuit equations with time‐varying plasma impedance and energy conservation laws to resolve spatiotemporal distributions of plasma pressure and shock wave energy conversion. A 3D fracture mechanics framework reveals critical insights: Increased principal stress difference (1–4 MPa) reduces crack width by 15.7% and fracture area by 18.9%, while higher injection rates (0.25–0.75 m 3 s −1 ) expand fracture zones; and simulations involving multiple cracks demonstrate that enhanced stress shadowing elevates the initiation pressures of two cracks by 13.48%. Experimental validation confirms model reliability (<5% error), demonstrating EHS's capacity to enhance fracture connectivity and energy transfer efficiency. These findings establish a theoretical foundation for optimizing EHS‐hydraulic fracturing in deep low‐permeability coal seams, addressing challenges of conventional techniques through improved controllability and reduced environmental impact.